SCIENTIFIC COMMITTEE, SEPTEMBER 23. 



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SCIENTIFIC COMMITTEE. 



September 23, 1902. 



Dr. M. C. Cooke, M.A., V.M.H., in the Chair, and seven members 



present. 



Diseased Helianthus. — Stems of Hclianthus exhibited were rotting at 

 the base and dying off in great numbers. Dr. Cooke pointed out that 

 externally there were, here and there, traces of. white mould, but 

 when cut down longitudinally the pith was found to be occupied by 

 numerous sclerotia similar to and perhaps identical with those found in 

 Potato-haulms and Tomato-stems, and these appear to be quite sufficient 

 to account for the dying off. This Potato disease is fully described 

 in Worthington Smith's " Diseases of Field Crops," p. 15, and the 

 life history of the sclerotium given, in which it is shown that the 

 ultimate development is a small Peziza, there called Peziza postuma, but 

 undoubtedly the same as had previously been described as Peziza 

 Libertiana, and more recently called Sclcrotinia Libertiana, and by Masses 

 as Sclerotinia Sclerotiorum (see Massee's " Plant Diseases," p. 150, fig. 32). 

 It seems to be found indiscriminately upon plants of various kinds, but 

 commonly on Potato and Tomato, Chrysanthemum, Cucumber, Turnip, 

 and Sunflower, 



Pear Disease. — The Pears sent to the last meeting, cracked, shrivelled, 

 and blackened by the attacks of Fusicladium pyrinicm, were reported 

 upon by Dr. Cooke as follows : — " In no case could I find any evidence 

 of the presence of the Entomosporium, which produces similar results. 

 It is noteworthy that, intermixed with the Fusicladium, were found 

 profusely the hyaline, curved, and septate conidia of some species of 

 Fusarium, which certainly bears no relationship to the Fusicladium, 

 and would be a distinct parasite. This requires further investigation, 

 since many of the species of Fusarium are destructive parasites, and this 

 has every appearance of being a new and undescribed species." 



Leaf -spot of Celery. — Leaves of Celery were exhibited spotted with 

 somewhat orbicular bleached spots, at first brownish, and then whitened 

 towards the centre. Dr. Cooke pointed out that scattered over these 

 spots are the minute black dots which represent the perithecia, enclosing 

 the sporules. These are not so numerous as in most other species, and 

 the sporules are long and thread-like, oozing out in a tendril in damp 

 weather (35-40 x 1-2 /a). It is the same species which occurs on 

 the leaves of Parsley, and is known as Septoria Petrosclini, Desm. It 

 occurs also in France, Belgium, Germany, Italy, and South America. 



Abnormal Pear. — Rev. W. Wilks showed an instance of a fleshy fruit- 

 like growth resulting from a double flower. The end of the flower-stalk 

 in these cases becomes fleshy internally, but externally bears leaves in 

 successive whorls one above another, like so many calyces. No true fruit 

 or seed is formed. The condition is not uncommon. 



